Hi,
> -----Original Message-----
> From: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>
> Sent: Thursday, November 18, 2021 9:18 PM
> To: Xu Yang <xu.yang_2@xxxxxxx>
> Cc: linux@xxxxxxxxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx; linux-
> usb@xxxxxxxxxxxxxxx; Jun Li <jun.li@xxxxxxx>; dl-linux-imx <linux-
> imx@xxxxxxx>
> Subject: [EXT] Re: [PATCH] usb: typec: tcpm: fix tcpm unregister port but
> leave a pending timer
>
> Caution: EXT Email
>
> Hi,
>
> On Thu, Nov 18, 2021 at 05:23:52PM +0800, Xu Yang wrote:
> > @@ -6428,6 +6432,9 @@ void tcpm_unregister_port(struct tcpm_port
> > *port) {
> > int i;
>
> You need to take the port lock here, no?
>
> mutex_lock(&port->lock);
>
> > + kthread_destroy_worker(port->wq);
> > + port->wq = NULL;
>
> mutex_unlock(&port->lock);
I think we should not take the port lock before kthread_destroy_worker() since a deadlock might occur. Considering a work is pending and tcpm_unregister_port is called at this time, the worker needs to flush all the works after taking the port lock in tcpm_unregister_port(). However, the work can't take the port lock anymore.
Xu Yang
>
> > hrtimer_cancel(&port->send_discover_timer);
> > hrtimer_cancel(&port->enable_frs_timer);
> > hrtimer_cancel(&port->vdm_state_machine_timer);
> > @@ -6439,7 +6446,6 @@ void tcpm_unregister_port(struct tcpm_port
> *port)
> > typec_unregister_port(port->typec_port);
> > usb_role_switch_put(port->role_sw);
> > tcpm_debugfs_exit(port);
> > - kthread_destroy_worker(port->wq);
> > }
> > EXPORT_SYMBOL_GPL(tcpm_unregister_port);
>
> thanks,
>
> --
> heikki
